SYNTAX ZX80'
A PUBLICATION OF THE HARVARD GROUP
VOL. 3 NO. 5 ISSN 0273-2696 MAY, 1982
IN THIS ISSUE
Important Notice . 17
4K Programs
IC Inventory . 18
8K Programs
ZX81 Intro . 17
Beginners Columns
BASIC-Inkey$ . 8
ML-Register/Register . 1 6
Classified Ads . 20
Dear Editor . 10
FORTH on ZX8l . 9
Hardware Projects
Memory Decoding . 5
Problem-Solvers . 6
2K Conversion . 14
Logic Chip Failure . 4
Microsync Speaks . 14
News, New Products .. 1 , 2 , 4
Numbers Held Inexactly.. 3
Program Corrections . 2
Program Improvements .... 2
Removing ICs Cheaply... 20
Software Review
New England Software. 19
Subscription Info . 23
Tips and Hints
Hardware . 2,3,18,19
Software . 17
Users' Groups . 2
Index of Advertisers
Bani-Tech . 3
LJH Enterprises . 17
Kopak Creations . 16
Memotech Corp . 7
S&S Co . 15
Sinclair Research... 1 2 , 1 3
Softsync . 3,11
Zeta Software . 8
Bindaii- inaa
Timex, the watch company that has always
built Sinclair computers, will market and
distribute Sinclair-based products in North
and Central America and the Carribean
beginning this year. Note the new name —
Timex-Sincla ir 1000. This computer is a
virtual twin to the ZX81, except for an extra
IK RAM under the hood (2K total).
Watch for these other changes:
Price — TS 1000 will sell for $99.95
assembled. There will be no more kits. 16K
RAM packs will go for $49.95.
Availability — Expect computers, software, and
peripherals from Timex to be in greater
supply than from Sinclair. According to the
agreement with Sinclair, Timex must meet
certain production levels (about 3x current
level). You will be able to buy computers,
etc., at Timex' 100,000 retail outlets,
including drug and department stores.
Other Products — Timex just announced
availability of two new products for 4th
quarter 1982: direct connect modem ($99.95)
and printer ($99.95). The printer shown at a
recent press conference looked identical to
Sinclair's UK ZX printer, although we expect
the shielding is improved to satisfy the FCC.
The modem will allow TS1000 and ZX'8l users to
access any phone-up data base.
Additionally, Timex plans to offer 25-30
assorted educational and business software
packages in July 1982, from $9 . 95-$1 9 . 95 .
According to Timex Product Manager Bill
Skyrme, Timex is very interested in customer
support. The TS 1000 will come with a manual
for beginning BASIC programmers. Timex will
continue Sinclair's 90-day warranty policy.
Service will probably be handled through
Timex' Little Rock, AR, facility, where
watches are repaired in 24 hours. We expect
Timex to maintain this level of service to
their computer customers.
Return your white renewal
card early for free
SYNTAX magazine binder.
1
SYNTAX ERRORS: Walter West reports
that Phone Number Generator
(Feb. 82) gives only 729 combina¬
tions as printed. Change line 110
to 110 NEXT Z to get all 218?.
PROGRAM IMPROVEMENTS
William Wentz of Rio Rancho,
NM, sent this improvement to Frank
O'Hara's Program 1 (from his
articles on Numbers Held Inexactly,
Mar. & Apr. 82). He says that on
ZX8ls with 3.25K of memory or less,
the variable VARS in line 20 is not
constant, but keeps moving up as
the display file (screen) is used.
To improve the program for any
memory size, change these lines:
15 FOR J=1 TO 5
30 LET IrV+J
50 NEXT J
NEW PRODUCT ANNOUNCEMENTS
F/22 Press now offers Dark-
star, a program to solve problems
for photographers in the dark-room.
You need a ZX81 with 16K RAM. The
program chooses exposure and
processing times for both black and
white and color work. Darkstar
tape and documentation, $99.95.
For free info, contact Robert
Martin, F/22 Press, P.O. Box 141,
Leonia, NJ 07605, 201/568-6250.
RKL Systems of Leominster, MA,
offers 16K RAM (expandable to 32K),
32K RAM, and single and double
joysticks for ZX80/8ls. Units are
fully assembled and tested. Joy¬
sticks come with directions for
machine code programs using joy¬
stick. Prices: 16K RAM — 79.95;
32K RAM — 149.95; single joystick —
69.95; double— 89.95; 16K to 32K
upgrade — 79.95. Special prices on
package deals. RKL Systems, P.O.
Box 515, Leominster, MA 01453.
Memotech Corp., Oxford, UK,
now sells their $179.95 64K RAM
pack in the US directly and through
distributors. It plugs directly
into the computer and runs off the
existing power supply. It provides
up to 15K of RAM for BASIC programs
with 32K left for arrays and vari¬
ables. Or you can cut back the
BASIC and fill up to 45K with
arrays. Another 8K can be used for
machine code or data without being
affected by NEW and RUN commands.
They also plan a 1 6K RAM pack,
high resolution graphics pack,
digitising pad, and RS232 and Cen¬
tronics interface. Memotech Corp.,
7550 Westyale Ave., Suite 220,
Denver, CO 80227, 303/986-0016.
USERS' GROUPS
Here's this month's list of
new ZX users' groups. Send us word
of your group and we'll send local
users to you. To locate a group in
your area, send us a SASE and we'll
tell you what we know. — AZ
Sacramento, CA: Contact William
Madden, PO Box 8201, Sacramento, CA
95818, 916/444-6780.
North Dakota: Contact K. Allen
Ward and Lonnie Misner, 520 Tulane
#205, Grand Forks, ND, 58201 .
St. Paul, MN: Contact Tom
Lindquist, 1740 Beechwood Ave., St.
Paul, MN 55116.
Indianapolis, IN: Contact Andrew
Thomas, 2804 E. 55th PI., Suite Q,
Indianapolis, IN 46220.
Memphis, TN: Contact Jimmie
Barker, 3791 Barron Ave., Memphis,
TN 38111, 901/327-2158.
Need fast ZX80/81 service? Jim
Burliegh of Dover, DE, reports that
National Electronics III fixed his
partially-assembled ZX8l kit for
$24.95 (2.5 hours work plus ship¬
ping). Door-to-door by UPS took 8
days. National Electronics III,
10425 Kingston Pike, Concord, TN
37922, 615/690-8927, Jeff Thompson,
manager .
2
NUMBERS HELD INEXACTLY ON THE ZX81
(Part 3 of Dr. O'Hara’s article)
What is the largest integer
a ZX8l holds exactly? The manual
is wrong in saying that 2^^ is the
largest. The largest is really
ie., this 39-digit num¬
ber: 1701411834208551504745551
34919112130560. Surprised?
The manual is trying to say
that every integer up to and
including 2^^ — not just 2^^-1 — can
be held exactly on the ZX81. More¬
over, 2^^ is the largest integer
for which this is true^ But every
even integer between 2^^ and
every multiple of 4 between 2^^ and
2^^, and in general, each multiple
of 2*^ between 2‘^and for n = 0,
1, 2, ...94 can be held ex a c 1 1 y .
And every multinle of 2^^ up to and
including can be held
exactly as well. 2'^'-2^^ is held
as 255,127,255,255,255 and you
can't squeeze another bit into
that; the one spare is needed for
the sign. Because of overflow and
another ZX81 oddity, you may have
difficulty in getting this number
into Program 1 (SYNTAX Mar.&
Apr. 82). This works:
2*(2**126-2**95+2**94)
But what of printing? 2^^+2
can be printed exactly: PRINT
2**32+2 (gives 4294967300). Armed
with this information, enter:
PRINT "42";2**32+2-42E8 This gives
4294967298, an exact result. But
2^^ (17592186044416) can't be
printed by this method, as 175921E8
is not divisible hy 2'^.
In theory, 2^’ could be so
printed, but a bit is lost in sub¬
traction on a right shift and is
not retrieved. The largest power
of 2 for which it works is 2^".
PRINT 2**39 gives 549755810000
and PRINT "5497'';2**39-5497E8 gives
the exact result 549755813888.
Moral: Don't believe everything
you read in manuals! Things can be
better, as well as, worse.
Frank O'Hara, Surbiton, UK
3
CUBE
A scientific approach to solving the
Cube. This program allows you to set up and move
the Cube in any configuration, gives you a choice of
displays -- two dimensional, three dimensional and
flat -- and remembers every move.
I6K $14.95
THE CHECK BOOK—
Get rid of the draw full of old checks^
and end the monthly hassle of checkbook balancing with THE
CHECK BOOK. This personal or business checking account
program stores up to 250 transactions on a single program. Over
3600 transactions can be permanently stored on a single cassette.
THE CHECK BOOK provides all transaction information and memos
and will sort by date, latest transactions or alphabetically.
I6K $14.95
BACKGAMMON
This classic game of skill and luck has
been transformed into an exciting ZX81 game using fast and
efficient machine code and detailed graphics. Backgammon has a
choice of four levels of skill and features screen displayed rolling
diceand doubling cube. 16K $14 95
CYBORG WARS'
Rule your own country on a small
asteroid in our galaxy. You are provided with secret reports of
resources like population figures, stockpiled arms and rations and
must utilize your Breeders, Farmers, Workers and Soldiers
effectively. If you do you may take over the entire asteroid. If you
don’t you’ll be faced with insurrection. Play against the computer or
VU-CALC
Turn your ZX81 into an immensely
powerful analysis chart. VU-CALC constructs, generates and
calculates large tables for such diverse applications as financial
analysis, budget sheets and projections. Using a choice of grids and
formulas you can quickly and easily set up an entire business or
household financial management program. ^ g|^ g gg
" “ "pLUriW^TlORT ScaT PROGRAMS “ "
WRITE FOR FREE CATALOG
Please send me:
_ copies of CUBE @ $14.95 ea
_ copies of BACKGAMMON @ $14.95 ea
► _ copies of THE CHECK BOOK @ $14.95 ea
_ copies of CYBORG WAR$ @ $14.95 ea
_ copies of VU-CALC @ $1,9.95 ea
Add $1.50 shipping and handling.
New York residents add sales tax.
SEND CHECK OR MONEY ORDER TO:
StJFTSYIVQUMC.
PQ Box 480 Murray Hill Station. New'ibrk.N.Y 10156
NAME _
ADDRESS _
CITY _
STATE/ZIP
SINCLAIR UK UNVEILS NEW COMPUTER
After much speculation about
Clive Sinclair's "ZX82," few were
prepared for his latest computer,
announced in London in late April.
Not the ZX82, but the SPECTRUM.
Besides the new machine, Sinclair
announced a reported 100K Micro¬
drive (3" floppy) for the end of
1982. They dropped their UK 16K
RAM price by £20, but raised the UK
printer price to £59.95. Sinclair
US won't know if their RAM prices
will drop until late May.
The 8x5x1" Spectrum machine is
memory-mapped and comes with 16K
ROM and 16K or 48K RAM on board
(16K is upgradeable to 48K with an
internal expansion board). It uses
a Z80A processor at 3.5 MHz. No
built-in flat screen TV yet. The
new computer offers 8 foreground
and 8 background colors and 10
octaves of sound through an inter¬
nal loudspeaker. The color display
is also memory-mapped and gives
normal or extra brightness and
flashing or steady mode.
Technically, the new machine
is not incompatible with ZX8ls, but
Spectrum uses a different, faster
(1500 baud) cassette interface, so
you cannot directly load ZX8l
tapes. According to Sinclair,
"ZX8l programs may be typed into
the Spectrum with minor changes."
The Spectrum will work with the ZX
printer, but not with Sinclair's
16K RAM pack. But it includes an
RS232 interface, so hooking up
other printers should be possible.
Also, Sinclair said Spectrum "may
be rendered teletext compatible."
The ZX8l's 8K ROM is a subset
of the new 16K ROM, so the 16K ROM
includes all features of the 8K
ROM, plus up to 52 user-defined
functions. Single keys control all
BASIC commands and functions, 16
graphics characters, 20 color codes
and 21 user-definable graphics
characters. The Spectrum also has
a full-size 40 moving-key ASCII
calculator-type keyboard with auto¬
repeat, and full upper/lower case.
SLOW and FAST are no more; the
Spectrum operates at the FAST mode
speed, but with a steady display.
It also has a VERIFY feature,
enabling you to check complete
storage of data and MERGE, which
combines programs in memory with
those on cassette. Other new
features include multistatement
lines, READ-DATA-RESTORE functions,
and a real-time clock.
Great, but what about the
important details? At first,
Sinclair will sell the Spectrum by
mail order in the UK only. Price:
£125 for 16K RAM and £175 for 48K
RAM. The optional 16 to 48K RAM
upgrade will be £60. Don't expect
to see the Spectrum machine in
North America until around December
1982, when Timex will presumably
handle it. US prices are not set,
but at press time the British pound
was worth about $1.70 US.
Sinclair also announced 26 new
ZX8I software packages developed by
ICL and Psion in England and avail¬
able in the UK in May. The pack¬
ages include record keeping, games,
and educational tapes. Most use
1 6K RAM. Expect these to be
available in the US in late May.
LOGIC CHIP FAILURE SYMPTOMS
Milton Halpern of Plainview,
NY, deduced that his ZX81 logic
chip (ICl) had failed from the key¬
board line and diode matrix.
Here's a chart of the symptoms:
KBD DIODE NUMBER
1 2 3 4 5 6 7 8
0--------
1 2 W 9 S 0 Z L .
23E8DIXKM
45R6GYVHB
Chart shows result of jumper
contact from KBD line to diode
number. "-" means oscillation or
blank screen. His K cursor was
normal at the start. He got a new
logic chip from Sinclair and now
the ZX81 works fine.
4
MEMORY DECODING ABOVE 16K
Sinclair made the ZX81 RAM
easy to decode up to 16K, but you
may want to add memory beyond this
point. To add more than 16K memory
to your ZX80/81, you must do more
than just:
aTs and Iv\ and aTs = ROM CS
You’ll also need to account for the
behavior of the display file.
If you decode your 1st 16K
block with A14=1 and A15=0, the
system crashes. ZX computers need
the display file active for dis¬
play, and the 8K ROM makes A15 high
during display. You can use the
relation :
A14 AND (Ml OR rr5)=RAM CS 0-16K
To get the second 16K block use;
aT4 and A15=RAM CS 16-32K
Get the 3rd 16K block using:
— BANI-TECH
Software of the Month Club
Get the most from your ZX81 with 16K, use it to
ifs full potential, while building an impressive in¬
ventory of software. Receive twelve Hsted programs—
one a month. Programs like Income Tax Recording,
Auto Maintenance, Household Expenses, Price of
Gold Forecasting, Diet Planning, Scrooge’s Christmas
Gift and Card List and many, many more for the
incredibly low price of just $19.95 per year. Save
your valuable time and get down to basics!
Make checks payable to BANI-TECH
P.O.Box 1568
Princeton, N.J. 08540
□ My check for $19.95 is enclosed.
Please charge my □ Mastercard □ Visa
Account Number _ Exp _
Signature _
Address .
A14 AND A15 AND M1=RAM CS 32-48K All Gates-- 74LS00
Sinclair RAMs lack this
decoding; you must add it to stack
16K modules.
Use of high-memory sites is
limited by the 8K ROM. You can’t
run Z80 machine language routines
here, nor extend the display file
past 32768. Store variables and
arrays in these high locations.
To find the end of the display
file,
PRINT PEEK 16400+256*PEEK 16401.
With the extended memory, you must
POKE 16388,255 & POKE 16389,255 &
NEW, after you power up, but before
you load any program. (The ZX8l
only checks memory addresses up to
32768, and sets RAMTOP there when
you power up.) If you poke RAMTOP
too high, your computer will set it
correctly after the NEW command.
John L. Oliger
Indianapolis, IN
Ml
32-48K
PROBLEM-SOLVING CIRCUITS
If your power line voltage is
120V or higher and you use a 16K
RAM, heat build-up in the ZX81 is a
problem. Reducing the power supply
voltage to the unit from about 10
VDC to 8V with a pre-regulator will
lower ZX81 regulator dissipation by
40%. Voltage above 8V is mostly
ripple and only heats up the ZX8l .
My pre-regulator was built
from junk parts, but commercially
available units should work as
well. The circuit in Fig. 1 is
adapted from National Semiconductor
Application notes. Use a suitable
heat sink with the LM 340-8.
If you're troubled by line
interruptions, a simple circuit of
4 or 5 silicon diodes in series
with a 12V car or boat battery will
take over on line failure and
prevent program loss. Any silicon
diode rated at 1A or above works
OK. Since the forward voltage
varies, try 4 or 5 in series to get
8-8. 5V into the ZX8l while
operating. A small trickle charger
will keep the battery charged, or
use a normal charger occasionally.
Or you could operate only
from the battery and not use the
plug-in ZX81 supply. The 9"
portable TV I use as a monitor also
operates directly from 12VDC.
Ed Buttenhoff, Grand Rapids, MN
Radio Shack #274-297 Radio Shack #274-286
1/8” Pin Jack 1/8” Pin Plug
From power
supply 10 VDC
8VDC to ZX81
FIGURE 1
On-off swi
+
4 or 5 1N4001 silicon diodes
8VDC output
to ZX81
Splice the output leads into the ZX81 power supply leads
or use a 1/8” Y adapter.
FIGURE 2
6
— -
Can you improve excellence?
We can. By adding our Memotech Memopak to the excellence of the ZX81
we have achieved perfection.
The growth of interest in computer use
caused by the introduction of the Sinclair
ZX81 has made new and exciting
demands on the ingenuity of electronic
engineers. At Memotech we have
focused our attention on the design of
inexpensive, reliable memory
extensions.
The Memopak is a 64K RAM pack
which extends the memory of the ZX81
by a further 56K. The new memory
extensions are designed to be within the
price range expected by Sinclair users. It
plugs directly into the back of the ZX81
and does not inhibit the use of the
printer or other add-on boards. There is
no need for an additional power supply
or leads.
Increase your memory.
The Memopak together with the ZX81
gives a full 64K, which is neither
switched nor paged, and is directly
addressable. The unit is user
transparent and accepts such basic
commands as 10 DIM A(9000).
m€noT€cn
Memotech Corp.
7550 W. Yale Ave.
Suite 220
Denver Co. 80227
Ph. (303) 986-0016
0-8K . . . Sinclair ZX81 ROM
8-1 6K . . . This section of memory
switches in or out in 4K blocks to leave
space for memory mapping, holds Its
contents during cassette loads, allows
communication between programs, and
can be used to run assembly language
routines.
16-32K . . . This area can be used for
basic programs and assembly language
routines.
32-64K . . . 32K of RAM memory for
basic variables and large arrays.
With the Memopak extension the
ZX81 is transformed into 3 powerful
computer, suitable for business, leisure
and educational use, at a fraction of the
cost of comparable systems.
Free service on your Memopak.
Within the first 90 days, should
anything go wrong with your Memopak
return it to us and we will fix or replace it
free of charge.
Try Memopak with no obligation.
You can use our Memopak in your
home without obligation. After 10 days, if
you are not completely satisfied, simply
return It for a full refund.
r„
ixg-
Mail to: Memotech Corp. 7550 W. Yale Ave. Suite 220 Denver, Colo.
80227
I understand that if I’m not completely satisfied, I can return my Memopak in 10 days for a
1
full refund.
Price
Oty.
Amount
Memopak 64k RAM
$ 179.95
□ Check
Memopak I6k RAM
$ 79.95
□ Visa □ MC
Shipping and Handling
$ 4.95 J
$ 4.95
Exp.
Total
Act. No. .
Signature _
Name_
Street
City
State
Zip
L
T U.S. Dollars
BEGINNER'S BASIC— INKEY$ FUNCTION
The INKEY$ function, though
more obscure than commands like
SAVE and RUN, is simple to use and
adds a nice touch to your programs.
INKEY$ plus a PAUSE command
causes your ZX81 to wait, watching
the keyboard until the user presses
a key. That key is then accepted
as input and the program proceeds.
Substitute INKEY$ for an INPUT
line. Say your program asks the
user to choose between 3 options.
Line 100 might read:
100 PRINT "CHOOSE THE MONTH YOU
WISH; 1. JAN 2. FEB 3. MAR"
You could follow this with
110 INPUT X
120 IF X=1 THEN GOTO...
130 IF X = 2 THEN GOTO... etc.
The user must press his desired
number, then ENTER or NEWLINE.
When the input is a single
digit, you can use the INKEY$ func¬
tion instead:
no IF INKEY$ = "1" THEN GOTO...
120 IF INKEY$r"2" THEN GOTO. ..etc.
Note that you must include " "
marks in the INKEY$ statement.
With this kind of input, the
user just presses his choice and
the ZX81 carries on. Reducing the
time and steps for input makes the
program simpler for the user.
You must also include a PAUSE
statement BEFORE the INKEY$ lines.
The PAUSE makes the computer wait.
Add a line like;
105 PAUSE 500
The ZX81 waits about 10 seconds for
input. Vary this time by changing
the number after the PAUSE.
Experiment to find a good time for
your program. If you have an old
8K ROM, add a POKE 16437,255 line
after the PAUSE. (To check your
ROM , see p.1 9. )
Keep this in mind: INKEY$
doesn't wait, so the user cannot
correct a mistake using the RUBOUT
key. Use INKEY$ for input when you
want a fast-moving program and your
user has little chance of error.
ZX81 OWNERS with 16K RAM!
IT'S READY— ARE YOU?
$14.95 +
2.50 S&H
If so. you get;
*24-row/fun-screen displays
*Near1y 2K of machine code
for FAST real-time graphics
*A 4K Star Atlas as the moving
backdrop during enemy engagements
16K Programs for either ZX80-8K or ZX81
*PLANE FRAME-model 1 ing for engineers
*FUNDAMENTAL ANALYSIS-for stocks investors
*P0LSAT & GEOSAT-space age Ham Radio uses
*MATH PAK-Routines & Fit, Variance Analyzer,
Statistics, and RPN Calculator
*E,S.P.-test your precognition
*Many others plus 6 IK 6-paks
including Machine Code
WRITE for free catalog. (In
Europe, send U$1 bill or DM2 stamp:
DELTAS0FT/0sterfeldstr.79D/D-2000 Hamburg 54 GER)
*9-each fuel and skill levels that
are interlocked for more "reality" ^
*4 ways to lose — no fuel, no oxygen, o
no gun power, or no shields. 1 way ^
to win — destroy ALL enemy craft. ^
*An enemy data generator imbedded in
the run as part of the "action" ^ -
*"Blink"-less pauses in BASIC
*Stick-on/peel-off custom keys
*In-depth booklet explaining both o =
the "game" and the program oj
*Shipped on a certified cassette q-co
1 copy each side
fTlail coupon or copy with payment to:
I ZETA Software/PO Box 3522/Greenvi 1 le,SC 29608
I Enclosed is $ _ DCheck □ _
I for - copy(ies) of SCOUT FIGHTER ZX81 16K
I plus $2.50 S&H for the order.
I NAME
ADDRESS
CITY/STATE/ZIP _
Please allow 4 weeks if paid by check.
8
PUTTING FORTH ON ZX80/81S
Although BASIC is the most
common language for programming
microcomputers, it is not the only
one. Your ZX80 or 81 can learn
FORTH, another high level language.
(For an intro to FORTH, check out
Byte Aug. 80.) FORTH has several
advantages over other languages in
certain applications, particularly
in computers as controllers.
Artie Computing announced that
they were developing FORTH on an
EPROM (erasable programmable read
only memory) for the ZX8l, to be
available in April. No word yet on
their success. The package, 2 4K
EPROMs on a board with users
manual, sells for £60, or about
$102 US. For info, contact Richard
Turner, Artie Computing, 396 James
Reckitt Ave, Hull, England HU8 OJA.
Richard Holmes of Batavia, IL,
has partially implemented FORTH on
his ZX80 with 8K ROM and 16K RAM.
He reports:
My starting point was Threaded
Interpretive Language by R.G.
Loeliger ($18.95 from Byte Books,
70 Main St., Peterborough, NH).
This book contains most of the
assembly code needed to implement
FORTH on a Z80-based computer. It
certainly makes the job easier, as
long as you watch for the occasion¬
al typo. The worst problem with
the book is that Loeliger's divi¬
sion routines are faulty.
The book doesn't give routines
to make FORTH work with the ZX80/81
configuration. I had to write 3
main machine-dependent routines —
$ECH0 (writes a character to the
screen), $KEY (displays the screen
and gets keyboard input) and BASIC
(returns control to the 8K ROM).
Some requirements: on return
from a USR call, registers lY and I
must contain 4000h and lEh. Of
course, SP must also be
undisturbed. HL' must also be
preserved. So on startup, FORTH
must save SP and HL'. Then when
the BASIC routine is called, it
must restore SP and HL', load 4000h
into lY (my FORTH code doesn't mess
with I, so no need to reset it),
and do a RET to get back to the
ROM. My version also calls a
routine that saves all the regis¬
ters in a block of RAM locations
you can PEEK. This helps enormous¬
ly when debugging.
$ECH0 and $KEY are based
around calls to ROM routines.
$ECH0 sets up a RST 10 call, which
takes care of writing to the
screen. You have to load 4000h
into
lY first.
$KEY calls routines
at 0229h (displa
ys screen), 0F48
( clea
ns up keyboard handling)
and
07BD
(decodes the keyboard).
Again
, 4000h mus
t be loaded i
nto
lY; a
Iso IX must
be preserved
be f 0 r
■e these cal
Is as the ROM
doesn
't preserve
it.
One other problem concerns
chara
cter sets.
FORTH is bas
ed
around the ASCII
(American Standard
Code
for Informa
tion Intercha
nge)
set w
hich includ
es characters
not
in the ZX8l set.
I defined an
ASCII
to ZX81 "m
apping"; I re
place
neede
d ASCII cha
racters with
invers
ZX81
characters
as follows:
ASCII
ZX81
ASCII
ZX81
a-z
A-Z
1
•
#
=
%
£
&
+
f
ft
@
9
[,]
(,)
\
/
—
>
{,}
<,>
Rich added that he would, discuss
putting FORTH on a ZX80/81 .'with
anyone who's interested. Send him
a SASE and $.50 to cover reproduc¬
tion of his materials. Richard S.
Holmes, 1303 E. Wilson Apt. 4,
Batavia, IL 60510.
Howard Gladstone of Gladstone
Electronic Distributors called to
say they remastered all their
tapes. Our review of their ZXAS
and ZXDB programs reported trouble
loading these tapes. This problem
should no longer exist for tapes
shipped after mid-April 1982.
9
DEAR EDITOR
You can use your Sinclair
computer to enjoy interactive
communications (games, program and
data transmitting/receiving) via
the phone lines by building the
very low-cost "Mickey Modem" as
described in the Nov. 1978 issue of
Kilobaud. Restrictions: both
parties must have a Mickey Modem
and use the same ROM; it only works
on local phone lines (no long
distance); and you must know your
receiver's RAM capacity (you can't
transmit 16K of program into IK of
RAM space. ..but the receiver's
modem could be hooked up to his
recorder and the program saved.).
Another goodie is the
"Computer Music Box Peripheral"
article in Popular Electronics ,
April 1978. It shows how to build
a low-cost, 12-tone, 4-octave music
generator that can be tied to an
output port such as shown in
SYNTAX, Jan. 81 p.7.
Let's dig out those cheapie
projects from old magazines we can
easily adapt to OUR computers!
Patrick Kelly, Los Angeles, CA
We haven't tried these projects. — AZ
Banta Software (RD #7,
Bethlehem, PA 18015) has 3 very
good programs on tape for $3.95 —
Football, Super Monzxer, and Murder
in the RAM. All are 16K, run well
and interesting to play. Banta
will make the tapes good if they
don't run. I had some trouble
with a tape and they worked with me
to get it running. I am happy with
these programs — for $3*95 you can't
go wrong. I will not recommend the
monopoly game.
Laverne Hoffman, Canby, OR
With the 1 6K RAM, the new
power pack is around 13.5-14V
(depending on line voltage). The
small electrolytic capacitor
adjacent to the 5V regulator is
rated at only 16V. After an hour
or so of operation, a small "worm"
crept up the TV display, typical of
poor DC filtration. I changed to a
470 mF at 25V for additional
filtration and a margin of safety.
My unit was reinstalled in a
custom case with aluminum front and
rear panels. I simply unbolted the
5V regulator from the PC board and
turned the heat sink around and
rebolted it to the rear chassis
panel. It runs cool as a cucumber.
It was heating the the adjacent ICs
after 15-20 minutes and causing the
system to crash. Taking it off the
PC board corrected this.
Glen DeLong, Moneta, VA
I would like to add a reverse
video switch and a video monitor to
my ZX8I as I did on my ZX8O. What
modifications and connections do I
need to make?
Ronald Swager, Springfield, IL
Unfortunately, you cannot simply
switch a ZX8l to reverse video as
you can a ZX80 (just a jumper on
the board). We do not know how to
reverse the video.
To hook up a video monitor,
pick up the video at pin 16 of IC1.
Pick up a ground somewhere (like
the modulator case). Connect these
to the composite video input of any
monitor with greater than, 1000 Ohms
input impedance. If the impedance
is 50-75 Ohms, add a buffer. Use a
source-follower or an emitter-
follower. — KO
I would like to praise the
repair department at Sinclair for
the fast, efficient and neat job
they did for me and my bungling.
Twice I damaged my ZX8l and/or RAM,
returned them with payment for
repair. They came back with remar¬
kable speed (2 weeks the first
time) and no additional bill. I
was amazed. Sinclair also replaced
10
a tape I could not get to load, at
no charge. I thank them from the
bottom of my RAM.
Also, a supply house called
Poly-Paks sells surplus computer
goods. Their parts are reasonably
priced and of good quality. They
tell you exactly what you're order¬
ing, such as "ICs 100% guaranteed,
untested." They are at 16-18 Del
Carmine St., Wakefield, MA 01880.
John Tiffin, Evanston, IL
It's good to hear that not everyone
has to wait interminably for ship¬
ments from Sinclair. If you're
waiting for a repair from Micro¬
sync, see the story on p.14. — AZ
of the connector must be partially
removed for the ZX81. I added home
brew memory using this technique
for connecting to the ZX80/81.
Hans Roensch
Editor's note: Having been accused
of running a catalog of things
impossible to procure, I'm happy to
report that The Fast One (data
management program from England),
reviewed in Apr. 82, is available in
the US from Mindware Inc. For a
free catalog, contact Mindware, 70
Boston Post Rd., Wayland, MA 01778,
617/358-7175.— AZ
COMPUTER CONTEST
The Radio Shack 276-1558 40- Win $100 for your scheme
pin card edge connector can be used involving a home computer. OCEAN
with the ZX80/81. The connector is looking for practical, revenue-
also requires the Radio Shack 40- producing ideas for any kind of
wire flat cable. This leaves 4 home computer. Deadline is 30 June
pins that must be hardwired to any 1982. For details, write OCEAN, PO
peripheral devices. The two ends Box 3221, Springfield, VA 22152.
d last, a comi
>nsive text for your
jpnplete BASIC Course is
will immediately become
an ihdisMnsible work of reference for all
your ZXW programming
Whether you have never done any
programming or whether you are an
experienced microcomputer user, the
Complete BASIC Course will provide
an invaluable aid
HOW TO WRIT! PROGRAMS
Even if the idea of writing programs is
completely mystifying to you, the Complete
BASIC Course will show you just how easy it
is. In rvD time you will be able to write and
enjoy complex programs for whatever you
desire
BASIC Course Programs
on Cassotts
All major programs in the BASIC Course are
available pre-recorded in this set of
cassettes.
SUKtoJa' SX«l
fetrtA. aQQm ivm&
Ih'. Uimi
Not Only so Programs for the
Sinclair zxsi: 1K —
Not only over 30 programs, from arcade
games to the final challenging Draughts
playing program, which all fit into the
unexpanded IK Sinclair ZX81 Great value!
Mochlno Language
Programming Made Simple for
the Sinclair —
A complete beginner's guide to the
computer's own language - Z80 machine
language, Machir^e lar>guage programs
enable you to save on memory and
typically give you programs that run 10-30
times faster than BASIC programs.
ZXB1 ROM Disassembly Part A
This book is for the programmer that needs
complete answers about the ZX81. Dr.
Logan has examined all routines in the ROM
and here he comments on each one It
covers all ROM locations from OOOOH to
OF54H, and includes all functions except for
the routines used in the floatir^ point
calculator.
ZX81 ROM Disassembly Part B
In this companion volume to Part A Dr.
Logan covers locations OF55H to IDFFH and
includes all routines used in the ZX81 floating
point calculator. These two books are a
must for the experienced programmer
understanding Your ZX81 ROM —
A brilliant guide for more experienced
programmers by Dr. Ian Logan, this book
illustrates the Sinclair's own operating
system and how you can use it.
The Complete BASIC Course has over
240 pages filled with information in an
attractive durable ring binder - this is a lay-
flat work of reference that deserves a
place next to every Sinclair ZX81
microcomputer.
NUM8ROUS RXAMPL8S
Every concept, every function is fully
described by simple programs that you can
enter on your Sinclair ZX81 in minutes
The Complete BASIC Course contains
over lOO programs and examples! These
programs illustrate the use and possibilities
of the Sinclair ZX81:
• Home use
• Financial analysis and planning
• Educational applications
• Games
• Mathematical applications
• Displays of Artificial Intelligence'
■VRRV FUNCTION COVBR8D
No matter what your application, what your
confusion about any function, you will find it
covered in the Complete BASIC Course.
The Complete
Sinclair ZX81 BASIC Course $35.0X3 0
Basic Course
Programs on Cassette S5.00 □
Not Only 30 Programs/Sinclair
ZX81:1K $14.96 □
Machine Language
Programming Made Simple $19.95 □
ZX81 ROM Disassembly Part A $14.95 Q
ZX81 ROM Disassembly Part B $14.95 O
Understanding Your ZX81 ROM $19.95 f")
PQ Bax 480i Murray HSI Statioa
NewM>X,N.YX)156
NAME
ADDRESS
Shipping and handling
Sales tax (NY residents only)
■ Mathematical and scientific functions
accurate to 8 decimal places
■ Unique one-touch entry of key words
like PRINT. RUN and LIST
■ Automatic syntax error detection and
If you already own a ZX80
The 8K Extended BASIC
chip used in the ZX81 is available
as a plug-in replacement for your
ZX80 for only $39.95, plus shipping
and handling— complete with new key¬
board overlay and the ZX81 manual.
So in just a few minutes, with no
special skills or tools required, you can
upgrade your ZX80 to have all the
powerful features of the ZX81. (You’ll
have everything except continuous dis¬
play, but you can still use the PAUSE
and SCROLL commands to get moving
graphics.)
With the 8K BASIC chip, your
ZX80 will also be equipped to use the
Introducing
the Sinclair ZX81
If you’re ever going to buy
a personal computer, now is the
time to do it.
The new Sinclair ZX81 is the
most powerful, yet easy-to-use
computer ever offered for anywhere
near-the price: only $149.95* completely
assembled.
Don’t let the price fool you. The
ZX81 has just about everything you
could ask for in a personal computer.
A breakthrough
in personal computers
The ZX81 is a major advance over
the original Sinclair ZX80— the world’s
largest selling personal computer and
easy editing
ZX Printer and Sinclair software.
the first for under $200.
In fact, the ZX81’s new 8K Extended
BASIC offers features found only on com¬
puters costing two or three times as much.
Just look at what you get:
■ Continuous display, including moving
graphics
■ Multi-dimensional string and numerical
■ Randomize function useful for both
games and serious applications
■ Built-in interface forZX Printer
■ IK of memory expandable to 16K
The ZX81 is also very convenient
to use. It hooks up to any television set
to produce a clear 32-column by 24-line
display. And you can use a regular
Order at no risk**
We’ll give you 10 days to try out
the ZX81. If you’re not completely satis
tied, just return it to Sinclair Research
and we’ll give you a full refund.
And If you have a problem with
your ZX81, send it to Sinclair Research
arrays
cassette recorder to store and recall
within 90 days and we’li repair or replace
* Plus shipping and handling Price includes connectors proqrams bv name ^10 Charge
for TV and cassette. AC adaptor, and FREE manual, ^ ’ -Does not apply to ZX81 kits. *
NEW SOFTWARE:Sinclair has
published pre-recorded pro¬
grams on cassettes for your
ZX81, or ZX80 with 8K BASIC.
We’re constantly coming out
with new programs, so we’ll
send you our latest software
catalog with your computer.
ZX PRINTER: The Sinclair ZX
Printer will work with your ZX81,
or ZX80 with 8K BASIC. It will
be available in the near future
and will cost less than $100.
16K MEMORY MODULE:
Like any powerful, full fledged
computer, the ZX81 is expand¬
able. Sinclair’s 16K memory
module plugs right onto the
back of your ZX81 (or ZX80,
with or without 8K BASIC).
Cost is $99.95, plus shipping
ZX81 MANUAL: The ZX81
comes with a comprehensive
164-page programming guide
and operating manual de¬
signed for both beginners and
experienced corriputer users.
A $10.95 value, it’s yours free
with the ZX81.
and handling.
Introducing
the ZX81 kit
If you really want to
save money, and you enjoy
building electronic kits, you
can order the ZX81 in kit form
for the incredible price of just
$99.95* It’s the same, full-featured
computer, only you put it together
yourself. We’ll send complete, easy-
to-follow instructions on how you can ^
assemble your ZX81 in just a few hours.^
All you have to supply is the soldering iron
How to order
Sinclair Research is the world’s larg¬
est manufacturer of personal computers.
The ZX81 represents the latest
technology in microelectronics, and it
picks up right where the ZX80 left off.
Thousands are selling every week.
We urge you to place your order
for the new ZX81 today. The sooner you
order, the sooner you can start enjoying
your own computer.
To order, simply call our toll free
number, and use your MasterCard or VISA.
To order by mall, please use the
6pupon. And send your check or money
order. We regret that we cannot accept
purchase orders or C.O.Dis.
CALL 800-543-3000. Ask for op¬
erator #509. In Ohio call 800-582-1364.
In Canada call 513-729-4300. Ask for
operator #509. Phones open 24 hours
a day, 7 days a week. Have your Master-
Card or VISA ready.
These numbers are for orders
only. For information, you must write to
Sinclair Research Ltd., 2 Sinclair Plaza,
Nashua, NH 03061.
PRICEt QTY. AMOUNT
105SX
TOTAL
MAIL TO: Sinclair Research Ltd., One Sinclair Plaza, Nashua, NH 03061
NAME
ADDRESS
CITY/STATE/ZIP
t U S. Dollars
$149.95
_ _ ^ ^
2X81 Kit
99.95
Hr 8K BASIC chip (for ZX80)
39.95
Fi6K Memory Module (for ZX81 or ZX80)
99.95
Shipping and Handling
4.95
$4.95
2K CONVERSION WITH 6116S
MICROSYNC SPEAKS
While assembling my ZX81, I
noticed the provision for adding a
2Kx8 RAM. While soldering sockets
to the PC board, I included both
the 1 8-pin sockets for the 2114s
supplied with the kit, and a 28-pin
socket for the alternative memory.
(The middle plastic portion of the
28-pin socket must be cut out so it
fits over and around one of the 18-
pin sockets.)
I ordered a 6116 2K memory by
mail. When it arrived, I simply
replaced the two 2114s with the
6116. The conversion was simple
and works fine. I can now fill the
screen with graphics!
My only problem was assuming
that the position of jumper J1 on
the PC board corresponded with that
shown on the schematic. It didn't.
When you install the jumper, make
sure to use the component I.D.s
printed on the PCB front.
Insert the 24-pin DIP with the
proper orientation and in the lower
24 pins of the 28-pin socket
(similar to the 8K ROM).
I used the Hitachi HM6116P-3
2Kx8 static CMOS RAM from Jameco
Electronics (1355 Shoreway Rd.,
Belmont, CA 94002, 914/592-8097,
hrs Mon-Sat 8-5 PST). Actually,
their catalog lists the device as
P-4, but I received a P-3 and it
works great. Cost: $14.95 plus $1
postage, $1.50 insurance ($2 each
postage and insurance for foreign
orders), plus 6% tax (CA only). A
data sheet is $.25 extra.
I'll use the 2114s for another
project, but have toyed with the
idea of a 3K conversion. This
would involve stacking the 6116 on
two sockets to put it above one of
the 2114s. Then some PCB traces
would have to be cut and two RAM CS
signals created. My prototype
requires only an additional 74LS00
to generate them from the existing
RAM CS and A1 1 .
Paul J. Brogger, Tumwater, WA
Yes, Virginia, there is a
Microsync. SYNTAX arranged an ex¬
clusive, secret interview with Bob
Allen, Service Manager.
Microsync exists to sevice
Sinclair computer equipment. Now,
about 12 people repair up to 100
machines daily. Most are kits,
although less than 1/5 of kit-
builders need service assistance.
Many readers ask if ULA (IC1)
chips fail more often than others.
Bob Allen tells us all chips get
replaced with equal frequency in
both kit and factory-built units.
ULAs do fail more often if instal¬
led backward. Although LOAD/SAVE
problems can result from ULA
failure. Bob says they usually have
some other cause.
From experience to date. Bob
feels the maintainance pricing ac¬
curately reflects the reliabilty of
Sinclair computers.
Microsync's goal is to
receive, repair, test and ship most
machines in 4 working days. Dur¬
ing this startup phase. Bob says
delays do reach 3-4 weeks. Just
before press time. Bob told us they
were servicing items that arrived 5
days earlier.
When your machine arrives.
Microsync date-stamps it immediate¬
ly. Unless the computer was pre¬
viously serviced unsatisfactorily
by Microsync, your computer moves
to service in this date order.
At the service area. Microsync
dates the order and begins repairs.
When done, each repair goes through
a QC test by the lead technician.
Next the machine moves to an
outgoing area where operators key
administrative data into the compu¬
ter system. Within 24 hours, the
shipping papers are printed and the
machine entered for UPS shipping.
This is basically a first-in,
first-out system and locating your
unit prior to completion requires
looking through the boxes. Bob
offers this advice when you must
14
check the status of a repair: Use
EXACTLY the same name, include your
ZIP code, tell EXACTLY when you
sent your unit, whether you used
parcel post or UPS, and if your
unit is a kit or factory-built.
Bob also points out that
Microsync will need 3 days to get
your reply in the mail to you.
SYNTAX offers additional tips:
• Photocopy the front of the box
before you send it. If you in¬
quire, send the photocopy with your
letter .
• Make a packing slip for the
package you send, and keep a copy
to send if you must inquire.
• Send your computer by UPS and
insure it. Use UPS Blue Label for
faster shipping (2 days).
Bob says common shipping prob¬
lems result from using flimsy boxes
or failing to write your name on
the box as well as the wrapping
paper. He suggests you use the
Sinclair box if possible. Further,
shipping to Sinclair in Nashua
gives you no advantage.
Only computers with damaged
boards are returned by Microsync as
unrepairable, according to Bob.
About li of machines come back
to Microsync as not properly re¬
paired. Bob suggests you return
the machine in their box, making it
clear that this unit has been in
before. Many returns are "no prob¬
lem found" cases where the customer
omitted the power supply and the
power supply is the problem.
Power supply problems can
cause a number of symptoms, includ¬
ing LOAD/SAVE problems with the 16k
RAM attached, left-to-r ight bars
that slowly rotate on the screen,
and others. If you have access to
a regulated power supply with plen¬
ty of current capability and low
ripple, substitute it and see if it
cures your problem. If you test
the power supply yourself, check
for increased ripple as well as for
proper voltage.
Bob Allen says: "If it's under
warranty and works except with the
SYNCH RO-SETTE
FORTHEZX-80&ZX-81
8KROM IK - 16K
GAMES-EDUCATIONAL-BUSINESS
GRAPH ICS-TUTORIAL-ETC.
24 HR HOTLINE - 800-543-1300
IN OHIO -800-582-1364
Ask for operator No. 383
1 2 monthly issues - 6 bi-monthly
cassettes containing at least 6 programs each
$39.50
ILL. Residents add $2.07 tax
outside USA add $10.00
s&sco.
388 West Lake Street • Addison^ IL, 60101
(312) 628-8955
RAM, send ALL the pieces."
If you installed an R-PAK
wrong in your kit, SAVE THE BOARD
AND SACRIFICE THE R-PAK. Don't
attempt to remove multiple-lead
components without de-soldering
tools. Solder-wick won't suffice.
SYNTAX asked Bob what causes
delays in service. He replied:
"The worst thing is money separate
from the unit." He explained that
this puts the unit in a hqlding
area, generates a letter to the
sender, and may require a'search of
other correspondence to locate the
payment. All of this is labor-
intensive and time-consuming.
LOAD/SAVE problems and RAM
problems take more diagnostic time.
Also, machines with no problem
found get extra testing to avoid
returning defective machines and
annoying customers. Machines re¬
quiring estimates also suffer
delays for correspondence. Kits
with "white screen syndrome" also
take longer to diagnose.
15
KOPAK GIVES
YOU THE
POWER!
KOPAK ’STM Touch-A-Matic gives you
KOPAKTM is now offering The Source*
the power to type more accurately and
‘America’s Information Utility’. The
much taster. No wires, no soldering,
Source* gives you the power to access
simple to install. Our unique vinyl over-
a wide array of services including:
lay guides your fingers to the correct
• Barter • Shopping • Business Infor-
keys. Touch typing now possible with
mation • Career Network • Electronic
your Sinclair* or MicroAce*!
Mail • Medical Advice • UPl News
$9.95
Service and much more. A modem is
required to use The Source*.
The KOPAKTM Sinclair* female Con-
Source ID $100.
nector gives you the power to use the
Z-80 bus. Edgecard connectors specif-
More POWER on the way! KOPAK’STM
ically made for Sinclair* computers.
Coming Creations:
• 46 Pins, 23/23 • All pins are gold
The KOPAKTM rs-232 Interface
plated • polarizing pin for correct
The KOPAKTM Bus
alignment everytime! Available with
The KOPAMATICTM Keyboard
Solder-Tail, Wire-Rap and PCBoard.
The KOPAKTM Printer
$14.95
KOPAKTM Memory Products
The KOPAKTM Disc
KOPAK has the POWER to deliver! ’
© 1982 KOPAK Creations Inc.
KOPAK Creations Inc.
TM Trademark of KOPAK Creations Inc.
Dept. SX
Sinclair* is a trademark of Sinclair*
448 West 55th Street
Research LTD.
New York, NY 10019
MicroAce* is a trademark of MicroAce*
(212) 757-8698
BEGINNERS’ ML — REGISTER TO REGISTER
(Number 5 in a series)
There are more than 100 1-byte
instructions for data manipulation
between single registers. These
are grouped as "LD r,r"; "ADD r,r";
"SUB r" (from A); logical opera¬
tions (AND r, OR r, and XOR r); and
"CP r" (comparisons to A). Here
we’ll look at loading, adding and
subtracting .
LD r,r is the general instruc¬
tion for data transfers between
single registers. That means that
values must be less than 256,
because no single register can hold
more than 8 bits, or a value of
255. Register pairs are just
that — two 8-bit registers.
Before you can transfer data
with an instruction such as LD C,E
(load data in E into C), the E
register must have data in it. In
practice, all registers have data
in them at all times, but rarely
the data you want. So you must
load the "source" register (E in
our example) with data before
moving
it to the
"destina
tion"
registe
r (C in our example).
Adding and subtracti
ng single
registe
rs are sim
lilar in
that all
operations are be
itween the A regis-
ter (Ac
cumulator)
and the
other
single
registers
(B,C,D,E
,H, or L)
or the
HL registe
!r pair.
(ADCs and
SBCs are identical to ADD
s and SUBs
except
that they
include
the Carry
bit in
the Flags
register
'.)
Fo
r example,
. let’s 1
oad B with
132, C
with 45 , a
ind D with 36.
Then we
:’ll add B
and C and subtract
D twice
i •
* •
REM ADD
. DECIMAL=
MNEMONIC
COMMENT
xxl
6
LD B,n
xx2
132
(data)
xx3
14
LD C ,n
xx4
45
(data)
xx5
22
LD D,n
xx6
36
(data)
xx7
120
LD A,B
; B to A
(A=132)
xx8
129
ADD A,C
;C+A=177
(A=177)
xx9
146
SUB D
;A-D=141
(A=141 )
xIO
146
SUB D
;A-D=105
(A=105)
REM ADD lists relative addresses.
You can find the decimal codes for
instructions in your 8K ROM or ZX8l
manual. Appendix A (the character
set). The first and third columns
list decimal code and corresponding
Z80 mnemonic. These codes also
serve as character codes, in BASIC.
You can find explanations for in¬
structions in assembly language
manuals such as Zilog’s Z-80 Assem¬
bly Language Programming Manual.
After "running," A will con¬
tain 105 while B,C and D will all
contain their "loaded" values.
Except for the A and Flags regis¬
ters, all registers keep their data
intact until specifically altered.
Next month: Exchanging Registers
Jon Bobst, Zeta Software, P.O. Box
3522, Greenville, SC 29608-3522
16
ZX81 INTRO
BYTESAVERS HINT— 8K
Here is a little subroutine I
use at the beginning of user-
friendly programs. Just RUN to
start or call it from within your
program by GOTO 60 or GOSUB 60. If
you use GOSUB 60, change line 270
to RETURN and delete 999. To stop
execution in midstream, press
BREAK.
This routine uses just about
exactly IK RAM.
A. Kohlenberg, Fremont, OH
60 PRINT RT I RM Z
65 PRUSE 10©
70 PRINT
80 PRINT "I RM R HOME PERSONRL.
COMPUTER"
85 PRUSE 150
9© PRINT
100 PRINT "I CRN DO MRNY THINGS
AND" ^ "THE BEST IS***^“
105 PRUSE 15©
110 CLS
120 PRINT
130 PRINT "I NEUE MAKE MISTAKE
S"
135 PRUSE 100
140 PRINT AT 2,7; "WHOOPS"
145 PRUSE 100
150 FOR Y=25 TO 7 STEP -1
160 PRINT RT 2,Y;"S"
170 PRINT RT 2,Y; " "
180 NEXT Y
190 PRINT RT 1,6; "jS"
200 FOR R=18 TO 1 STEP -1
210 PRINT RT R,6;"R“
220 PRINT RT R,6;" "
230 NEXT R
240 PRINT RT 1,6; "R"
250 PRINT RT 10 , 8; "WEL.L. , RI_MOSX
NEWER"
260 PRUSE 150
270 PRINT RT 11, 15; "BYE"
999 STOP
SYNTACTIC SUM: 33973, 8K
ATTENTION SUBSCRIBERS: Some makers
and distributors of ZX-related
products have asked about mailing
to our subscription list. We think
you would find some of these mail¬
ings useful or informative. How¬
ever, your name and address are
private (the reason we don't print
complete addresses unless asked to
by the person). If you would not
like to receive such information in
the mail, please let us know. If
we don't hear from you, we'll pre¬
sume you would like to receive ZX-
related literature by mail. — AZ
If you are using a PRINT after
a line number simply to add an
empty line, use two commas instead.
Often empty lines are useful to
clean up a screen display. These
two programs display the same
spacing — the second saves you four
bytes :
Program 1
10 INPUT A
20 PRINT A
25 PRINT
30 INPUT B
40 PRINT B (bytes used=34)
Program 2
10 INPUT A
20 PRINT A
30 INPUT B
40 PRINT ,,B (bytes used=30)
Each substitution of commas for
blank PRINT lines saves four bytes.
Dave Hallas, Kansas City, MO
NOW AVAILABLE
keyboQfd .
^ ^conversions
• Standard Computer Keyboard
• Type programs in half the time
• Minimize errors
• Wired keyboard hooks up in minutes
Plans for keyboard conversion with reverse video
NOW $5.00
Keyboard with complete parts and plans NOW $55.00
Wired keyboard, complete with plans MW $75.00
Add $5.00 mailing charge for continental U.S.
Other locations write for details.
Mail for information:
LJ.H. Enterprises
P.O. Box 6305, Orange, CA 92667
or can 714/547-8717
17
IC INVENTORY — 4K/2K
Some hobbyists have trouble
keeping track of parts. This
program, written for the CD4000
series of ICs and using the 4K ZX80
ROM and at least 2K RAM, can be
adapted for any series of things
following consecutive numbers. It
is beneficial to keep two lists for
each series — one of those in stock
and one of those used in circuits
for emergency substitutions.
The first part of this program
is also useful for setting aside
memory for machine code routines.
Enter line 1 :
1 REM 480 BYTES FOR DATA 0123
456789012345678901234567890
Then type EDIT, RUBOUT, 2, NEWLINE.
This duplicates line 1 as line 2 as
saves lengthy typing. Repeat
procedure for line 3.
Next POKE out the newline
characters at the ends of lines
1&2, combining all three into one
long REM statement for the data:
POKE 16477,61
POKE 16531 ,61
Then repeat the duplicating
procedure :
EDIT, RUBOUT, 2, NEWLINE
EDIT, RUBOUT, 3, NEWLINE
Set the memory behind the first REM
to zeros:
10 LET A=16426
20 FOR B=0 TO 480
25 POKE A+B,0
30 NEXT B
RUN
This leaves 1 REM on the screen
and about 2/3 blank, with 90 above
the E in line 10. Line 1 now has
482 data spaces available if
nothing larger than 255 is entered.
Do not enter quantities greater
than 255. Each quantity is held in
1 byte, with a 255 maximum.
Now enter the following
program. Note that line 25 is
changed. After pressing RUN, the
screen takes at least 5 seconds to
display.
Gyro Burns, Athens, OH
10 LET A=16426
15 PRINT, "CURRENT LIST"
20 FOR B=0 TO 480
25 IF PEEK(A+B)>0 THEN GO SUB
300
27 IF PEEK(A+B)>0 THEN PRINT,
30 NEXT B
40 PRINT
50 PRINT "FOR CMOS IC S"
60 PRINT "INPUT THE NUMBERS A
FTER CD4 — "
70 INPUT B
80 IF B>480 THEN PRINT "OVERR
ANGE"
85 PRINT
90 IF B>480 THEN GO TO 60
100 CLS
110 GO SUB 300
130 PRINT " IN STOCK"
140 PRINT "LIST OR CHANGE? L/C"
150 INPUT C$
155 CLS
160 IF C$="" THEN GO TO 45
165 IF C$="L" THEN GO TO 10
170 PRINT "TO WHAT?"
180 INPUT D
190 POKE (A+B) ,D
195 GO SUB 300
197 PRINT
200 GO TO 45
300 PRINT "CD4";
305 IF B<100 THEN PRINT "0";
310 IF B<10 THEN PRINT "0";
320 PRINT B,
330 PRINT PEEK(A+B);
350 RETURN
390 REM CMOS IC LIST 5/1/82
Syntactic Sum: -30692, 4K
To check that your 16K RAM pack is
working OK on your ZX8l, follow
these steps:
Pull the power jack and plug it
back in to clear the machine.
Type in the immediate mode (with no
line number) :
PRINT PEEK 16388+256*PEEK 16389
Press ENTER or NEWLINE.
If your 16K RAM is OK, the answer
on the screen is 32768. Try it
without the RAM attached. With
just the internal IK RAM, the
answer is 17408. This routine
checks to see where the top of RAM
is and reports the highest address.
18
SOFTWARE REVIEW— 8K/1K SLOT MACHINE
Here's another free sample
software review — a program directly
from New England Software's tape.
Try it out and see for yourself.
Part of a package available
for $10 on tape from the address
below, Slot Machine runs in IK, no
small feat for a game with its
features. The display could be
more elaborate, but only at tremen¬
dous memory expense. If you have
just IK on your 8K machine, you'll
be surprised at what it can do. — AZ
This program simulates a
dollar slot machine. RUN the pro¬
gram to start; to exit enter a
double letter such as ZZ instead of
a bet. Enter your bet each time.
The computer displays each window
in succession in SLOW. Six differ¬
ent symbols are used. Payoffs are:
W—2 to 1
5 to 1
3 of a kind — 20 to 1
Rather than giving you money
(who gives away money these days?)
the computer starts you at $0 and
tracks wins and losses. The pro¬
gram is set to pay back 95% of all
money entered, so sometimes you win
and sometimes you lose.
In lines 35, 45 and 50, use
keywords TO or AT. In subroutine
400 a FOR-NEXT loop is used instead
of PAUSE to prevent screen flicker.
To save valuable memory in IK,
nearly all numbers are expressed in
terms of D, E and F (already de¬
fined variables).
Here's a neat trick to save
memory. If you use a number sev¬
eral times in your program, replace
it with a defined variable. For
example, if you use 1 several
times, enter a line LET A=1. Use A
in place of 1 throughout your pro¬
gram, A-A in place of 0, A+A in
place of 2. You may be surprised
at how much memory you save.
Bob Ferguson, New England Software
Box 691, Hyannis, MA 02601
5 LET E=2
10 LET F=3
15 LET ^f=E-E
£0 RRND
25 LET D=RND^^E
30 IF D>=F-E THEN PRINT "TRY Y
OUR LUCK"
35 IF D<F-E THEN PRINT “PRY HE
TO UIN"
4-0 LET D=2©
4.5 PRINT “NOU RT : M
5© PRINT “PLRY $1 TO $5"
6© INPUT B
7© IF B<F-E OR B>E+F THEN GOTO
Ds-F
80 PRINT RT E-E^E-E;"i
90
10©
11©
120
130
14-0
15©
IS©
170
IS©
190
20©
210
22©
230
24.0
25©
270
280
290
300
31©
320
4.0©
4-10
Vi-,—
4-30
4-4-0
E*F;
D.-'E,
, E-E;
IF X < >Y OR X < >
PRINT
PRINT
PRINT
PRINT
PRINT
PRINT
GOSUB
LET X=R
PRINT TRB
GOSUB
LET Y=R
PRINT TRB
GOSUB E>^D
LET Z=R
PRINT RT F
LET H=H-B
IF XOF THEN
1 THEN GOTO O
250 PRINT "YOU
LET C=E
IF Y=F THEN LET C=E+F
IF X=Y RND X=Z THEN LET
LET M=H-S-C*B
PRINT C*B
GOTO D+D
P = 1NT {RNOJt {E«-F> >
FOR Z=:E-E TO 65
NE.XT Z
PRINT CHR* (128-fR*E) ;
_ RETURN
SYNTRCTIC SUM: 33186, 8K
(Line 80-all graphics space, 7, 7, 7,
space, etc. Line 90-graphics space,
3 normal spaces, etc. Line 100-all
graphics space , 6 , 6 , 6 , space , e tc. )
UIN
C=D
DEFECTIVE 8K ROMS: Brad Lange of
Enid, OK, reports that he and
friends bought 6 ZX8l kitsy Dec.8l -
Apr. 82. All 6 kits contained the
old 8K ROM with bugs. (Old 8K ROMs
give some arithmetic errors and
crash after PAUSE commands.)
Sinclair said they were unaware of
this problem and replaced their
ROMs free. Bruce Livett of
Montreal, Quebec, finally got his
replacement 8K ROM in Feb. 82 (or¬
dered Jun.8l ) and also found it was
defective. To check that your 8K
ROM is the new, corrected version,
type in PRINT PEEK 54. Old ROM
gives 132. Improved ROM gives 136.
Test from Ian Logan, SYNTAX Dec. 81
19
Paul Pittari reports that he
followed the Sinclair schematic for
the power converter in the 16K RAM
pack with 3 substitutions.
He used a TIP34A transistor to
replace the ZTX750, a 1N4007 to
replace the BA 221 , and an old AM
radio antenna to make the auto¬
transformer. He called later to
say the transformer loaded down,
12V dropped to 10V, so he had to
rewind it with heavier wire.
CLASSIFIED ADS
You can reach thousands of ZX80/81
users for just $9 a line. Send us
your ad copy, typed 35 char, per
line, with a check (NO CREDIT CARDS
OR PHONE ORDERS, please) by the
15th of any month. Your ad will
appear in the next month's issue.
To repeat an ad, send another ad
order with check by the 15th. We
have not seen all products offered
and take no responsibility for
advertisers. SYNTAX, RD 2 Box 457,
Harvard, MA.
7 IK ZX81 GAMES ON CASSETTE- -$ 10 . 00
Mastermind, Slot Machine, Craps,
Sub Rescue, White Hot Number, and
more. NEW ENGLAND SOFTWARE , Box 691,
Hyannis, MA 02601. (Also for ZX80)
AT LAST ! Programs for the collector;
Antique, Art , Baseball card, Beer can.
Book, Coin, Comic book , Football card.
Record album and Stamp. Mass Storage
Inventory . GUARANTEED easy loading.
Menu format . bistable . Search , Check
inventory , Total cost/value and more
ZX80/81/M.A. 8KROM/16KRAM. Cassette &
Manual . ^4. 95+1 . 05P . ea. M. C . Hoffman
P.O. Box 117, Oakland, N.J. 07436
NEW: For the ZX81 w/16K RAM Pac .
Geometry and graphic trig data,
resonance and matching calculations
+0hms Law; 6 programs (17K) in all!
Straight forward BASIC, use and
learn at the same time!
Send $14.95 to: SOFT-WAY
3308 Midway Dr. Dept. 124
San Diego, CA. 92110
REMOVING ICS SAFELY AND CHEAPLY
Instead of buying costly
tools for IC removal, get binder
clips (with springs). For less
than $.40, the large size will
handle 40-pin ICs; the small size
(less than $.20) works for smaller
ICs. The metal clip ties the pins
together, so no static problems
from plastic tools. The spring
tension bends pins inward slightly,
making them easier to put in sockets.
To remove an IC, put the clip
down to the top of the socket.
Gently pry up alternate ends of the
IC with a small blade or screw¬
driver to loosen it gradually. As
the pins emerge, slide the clip
down the legs for a better grip.
Lift the IC out and place it on
aluminum foil or conductive foam.
To insert an IC, hold it in
the clip and set the pins in the
socket. Press down gently in the
center of a small IC or on alter¬
nate ends of a large IC until it is
entirely seated. Be careful not to
bend the pins; they can snap off.
Herb Sturges, Orinda, CA
EZRA GROUP II
EZRA GROUP II
The ZX80/81's are making a name
with LOW prices . . .
WE CHALLENGE THE SOFTWARE COMPANIES
TO LOWER THEIR PRICES!
for ZX81/ZX80/8k ROM
IK and 16K RAM versions
Moving Billboard. ! ! SIDEWAYS! ! . . 1.00
Horse Race . 1.00
Quilt Painter. (from Keyboard) . .1.00
Metric Conversion . 1.00
Functorial Hypercube Course
with Programs . 1.95
Postage per order . 50
Self Addressed Stamped Envelope
Gets You Our Goodies Catalog
ALL ORDERS AND CATALOG REQUESTS GET
FREE PROGRAM.
EZRA GROUP II
EZRA GROUP II
P.O. Box 5222 San Diego, California
92105
20
ZX81 PROGRAMS- -All 6 fit IK RAM
HANGMAN word game, NIM number game
DICEPLOT simulator, CRAPS gambling
PRIME generator + FACTOR extractor
All quality programs.
NO TAPES! Save these yourself and
save money. Lis tings+instructions
ONLY $4. R. Howard 3752 Rolison #21
Redwood City, Ca 94063
BRITAIN'S BEST TEACHING SOFTWARE!
Programs for 4-12 graders at home
or at school - math, English,
French, science, history, etc.
Excellent reviews. Most cost £4.00
Send reply coupon for list to:
AVC SOFTWARE PO BOX 415 BIRMINGHAM
B17 9TT, UK
ZX81 16K SOFTWARE- -Send SASE for
discriptions . All cassette
BRITTANYSOFT LTD., P.O. Box 1043
Twin Falls, ID 83301 208-324-3086
NEW. . . ZX-CALC The new Electronic
Spread Sheet program for the ZX80,1
(w/8K,16K). This large sheet 30co.
X 45 li. can be adapted to may of
your needs: Budget, Inventory, For-
casting, Etc. This program on cass¬
ette is only : $16 . 00+1 . 50 postage +
handling. MAIL CK. or M.O. to:
SOFTWARE APPLICATIONS, PO BOX 1922
ATASCADERO, CAL. 93422
Female Connectors for Sinclair
Users. 23 dual pin keyed, WW or
eyelet avail. , please specify. $10
ppd. each, M.O. or check only. RG
Enterprises, PO Box 271173,
Escondido, Ca. 92027. Ca. res. add
67o sales tax.
PUT THAT ZX80/81 TO WORK with SORT.
This great collating tool can count
1000 's of items in up to 29 catego¬
ries on just IK! ! $3 gets you list/
explanation to learn/build on.
MAD DOG TANK BLASTER- ZX81-16K shows
you how to create that masterpiece
of your dreams. Moving tank-soldier
Bullets/explosions all explained. A
terrific game/a real idea generator
List w/complete instructions $6.95
TOM WOODS Box 64 Jefferson, NH 03583
A PLAYER ZX81 cassette , $6 . 95pp , with
your 8K-1K/16K system and recorder
become a 124 note MUSIC SYNTHESIZER
W Maples 688 Moore St LKWD,C0 80215
+>v*dISCOUNT ZX- 81 ( IK) PROGRAMS***
8 Programs on each. $8.00 a tape
TAPE ( 1) GAMES : Lunar Lander etc.
TAPE (2) DIET : Calorie Computings etc.
TAPE (3) HOME : House Security etc.
TAPE ( 4) BUS INE S S : Salary , Markup7o etc.
TAPE (5) MATH: Drills for all ages.
TAPE (6) GEOMETRY :Pythag. Ther. etc.
TAPE (7) DESIGN: Computer Clocks etc.
TAPE(8) INVESTMENT: Interest 7o etc.
TAPE (9) QUIZ : Various for all ages.
TAPE (10) GENERAL : 1 of each category.
ROMAN SOFTWARE 788 Mercury Circle
Littleton, Colo. 80124
BUFFERED EXPANSION BOARD for ZX80/1
BUFFERED EXPANSION BOARD for ZX80/1
For marketed and user built periph¬
erals. All lines fully buffered and
in same order as on Sinclair port.
Unique decoder circuit makes avail¬
able up to 8K of memory mapped I/O
addresses. Holds 6 card edge conne¬
ctors and has 1 set of gold fingers
.Has many on board circuitry and
mechanical options. Develop your
own peripherals with wire wrap on
readily available cards. Plans for
I/O port, A/D, D/A, DMA, More, will
be available soon. Write me of your
developments so that Expansion
Board users may benefit. Board is 2
sided, plated holes, tin plated,
legend, solder mask, 7x8 in. All
parts readily available. With
complete documentation. Available
as BARE BOARD (with connector to
computer) or KIT (with 8 I.C.s ,
sockets, 6 connectors , parts needed.
Immediate delivery while current
stock lasts. To order send check:
$33. . .BARE BOARD, $63... KIT, to
COMPUTER CONTINUUM, 301-16 Ave
San Francisco CA 94118. Calif res
add 6 l/27o tax. Send stamp for spec
sheet/photo; write or call (415)
7526294. EXTRA! UHF modulator $15.
Solves VHF interference problems.
Send to MODULATOR, same address.
Eric Reiter
21
ZX81 SOFTWARE ON CASSETTE
"Special Introductory Offer!"
12 IK Games on cassette with copies
of programs and full instructions:
DEPTH CHARGE , BLACKJACK , AUTO RACER,
MORTAR SHELL, THREE TOWERS , and more.
All for $6. 75'"’'*freE CATALOG with
first order or send SASE to* H & H
ELECTRONICS, 3379 Route 46, - 6D
Parsipanny, N.J. 07054
"ZX81 MONOPOLY" - Now available.
16K RAM - imported from the UK.
British board version family game.
$14.95-from Savage Software, PO Box
892, New Smyrna Beach, FL 32069
COMPUSETTE is a C-10 cassette which
is especially designed for micro¬
computer application by Tapemasters
IN TEXAS PHONE (214) 349-0081
FREE OUT-OF-STATE 1-800 527-1227
VISA MASTERCARD C.O.D.
25 FOR $20.00
100 FOR $70.00
500 FOR $330.00
10% DISCOUNT FOR CASH
MAIL CHECKS OR MONEY ORDER TO
TAPEMASTERS -POST OFFICE BOX 38651
DALLAS, TEXAS 75238
FREIGHT PREPAID*DEFECTIVES REPLACED
ZX81/80 WEATHER FORECASTER 8K 16K
Needs a Barometer . FORCAST 36 Hrs .
in advance . LISTINGS : $5+SASE Richard
Toy 546 CR. 214 Fremont, OH 43420.
V /\ /\ /\ /\ /V /\ ✓\ /\ /\ yv y\ /\ yv yv y\ yv y\ /\ yv /\ /V yv /\ y\
FASTEST SPACE WAR GAME YET I *
-81 Space Raiders for ZX81 with *
16K RAM. High speed graphical *
display of moving starfield and *
custom ML math package provide *
real time, accurate simulation *
of space navigation and battle. *
Only $19.95 for cassette, *
keyboard overlay, and manual. *
NIRAD ELECTRONICS, 959 East *
460 South, Provo, UT 84601 *
U •kU ^»a- ..fa- ^1-. ,^1--
V /V y\ y\ y\ y\ yv yv yv yv yv yv yv yv yv yv yv yv yv yv yv yv yv yv yv yv yv yC /\
^LOTS OF GRAPHICS**********
LAND THE SPACE SHUTTLE and LAND/AIR
BATTLE. Two games on one tape. $8. 85
*NEW* SPACE BATTLE. On tape... $6. 95
Games for ZX81 8KROM/ 16KRAM*FUNWARE
7119 Santa Fe Av. Dallas, Tx. 75223
EDGE CONNECTORS: Solder-eye or wire-
wrap , gold-pltd contacts- $7 . 50 , 5/ $30
*WIRING DIAGRAMS for attaching key-
boar ds&joy sticks to ZX81-$2. SMUG
PROJECT, Box 13042, Ft Wayne , IN 46866
Create GAMES to $ell! or DRAW/ERASE
Graphics. GOOD IDEAS/ INFO /FUN I Be a
part of huge new ZX80/81 Mrkt. Send
$2 & SASE: WSM PRODS. 4365 Ventura
Canyon Ave. Sherman Oaks, Ca 91423
MAXWELL'S DEM0N--an action game for
the ZX81 with 2K RAM. Send SASE for
details, $4 for tapes: A. Longacre ,
21 Leitch Ave, Skaneateles ,NY 13152
WORD PUZZLE-Guess phrase , title , name
by guessing 1 letter at a time Use
computers puzzles or opponents.
YAHTZEE- Challenging game of skill
+luck BOTH on cassette+ins tructions
+2 more f unprograms 8K/16K ZX80-81
Send $4.95 CK or MO payable to
A. Kohlenberg to: JAMM SOFTWARE
1301 SR 523#37 FREMONT, OH. 43420
8K/1K WORD PUZZLE Send SASE+$1.50
Turn your ZX81 into a full graphics
calculator able to display equation
with result! Short program only $1+
SASE : ZxCo . POB 138 Syosset , NY11791
ZX81 T- Shirts ! -Finest quality with
distinctive ZX81 logo emblazoned on
black field. Specify Sm,Med , Lg . $6 . 95
@, Check or MO +$lper order shipping
CUTS Co,P0 Bx 37 Mamaroneck , NY10543
EZ ZX typing/EZ switch to regul¬
ar keybrd. EZ PLANS. $3.& SASE:
WSM PRODS. 4365 Ventura Canyon,
Sherman Oaks, CA 91423
43 pin gold W/W edge connectors $4.
6116 150ns RAMS $10. List of more
items w/SASE. Postpaid from: Weick,
7127 W. Becker Ln, Peoria, AZ 85345
22
FOR SALE: ZX80 ROM Switch.
Run 8K or 4K Software at a flick
of the switch! Basic Kit: $24.95
Full Feature Kit: $34.95 (Includes
keyboard beeper & load processor.)
Marex Electronics , 2805 Abbeyville
Valley City, OH 44280
MAGIC SQUARE. World's Most Magic!!!
16x16 More Magic tn BEN FRANKLIN 's
Probe with ZX. $2.00 EZRA GROUP II
Box 5222 San Diego , California 92105
OUR POLICY ON CONTRIBUTED MATERIAL
SYNTAX ZX80 invites you to express opinions related to the ZX80 and the
newsletter. We will print, as space allows, letters discussing items of general interest.
Of course, we reserve the right to edit letters to a suitable length and to refuse
publication of any material.
We welcome program listings for all levels of expertise. Programs can be for
any fun or useful purpose. We will test run each one before publishing it, but we
will not debug programs; please send only workable listings.
In return for your listing, we will pay you a token fee of $2.00 per program we
use. This payment gives us the nonexclusive right to use that program in any form,
world-wide. This means you can still use it, sell it, or give it away, and so can we.
We will consider submissions of news and hardware or software reviews. Please
keep articles short (350-400 words). Again, we reserve the right to edit accepted
articles to a suitable length. We will pay 7 cents per 6 characters, including spaces
and punctuation, for accepted articles.
When you send in programs for possible publication in SYNTAX, please
include the following information:
• How to operate the program, including what to input if it does not contain
prompts.
• Whether you can run the program over again and how.
• How to exit the program.
• The Syntactic Sum (using the Syntactic Sum program in the February, 1981,
issue).
• Whether it fits in IK or 2K RAM (or 16K when available).
• Whether it uses the 4K or 8K ROM.
We pay for this explanatory text at the same rate as for articles in addition to
payment for the program itself.
If you want us to return your original program listing or article, please include
a self-addressed, stamped envelope. Otherwise, we cannot return submitted material.
SOFTWARE: Sinclair ZX81 cassettes #
1,3,4 (new factory cass.) 12-ganies,
3 B+H. No waiting! $27,415-387-1161
AFRICAN PILOT : Program mixes advent¬
ure & business :You battle jungle to
keep plane/profits UP: Graphics! $10
EXCITING FLIGHT SIMULATION PROGRAM:
Takeoff, land, outrun/ dodge hazard:
Realtime view : Plane/ Ins t rumen ts ! $10
HENSLEY, BOX 334,ASHEBORO NC 27203
Load ZX80/81/MicroAce everytime-LED
Monitor. Plans $2+SASE; Kit $6+$l
S6cH. Hold full load Ik for 25+
min. or full 16k for 10+ min. if
elec, faulters or fails. Plans $5+
SASE; Kit $19.95 +$1 S&H. R.H.
Enterprises, 1408 N.4th Ave. E.,
Newton, Ia--50208.
SOFTWARE - - - SOFTWARE
ZX80 - ZX81
Over 200 Programs From Physics And
Business to Games. For IK and 16K
List price from $.05 and Tape price
From $2.10
Send $ 1.00 for Catalog to:
Detron of Hawaii
2007 Naio Street
Honolulu, Hawaii
96817
The $ 1.00 good toward purchase
SYNTAX ZX80 is published
monthly by a wholly-owned
subsidiary of The Harvard Group.
Syntax ZX80, Inc.
RD 2, Box 457, Harvard, MA 01451.
Telephone 617/456-3661.
12 issues, $29. Single issue, $4.
Publisher: Kirtland H. Olson
Editor: Ann L. Zevnik
Printed by Joseph E. Marhefka, Jr.
Clinton Offset Printers
Clinton, MA 01510
© Syntax ZX80, Inc., 1981. All
rights reserved. Photocopying
prohibited. ISSN 0273-2696
YES! Please send me 12 issues of SYNTAX for $29.
□ My check for $29 is enclosed. □ Please charge my □ MasterCard
Make checks payable to: □ Diner’s Club □ American Express
SYNTAX ZX80, INC. □ VISA □ Carte Blanche account
{
account number _ ’ _
exp. date _ bank number (MC only) _
signature _
Name _ Title _
Organization _
Address _ _
City _ State _ Zip _
Day Phone_( _ ) _ Evening Phone_( _ ) _
ZX817S
I own a □ Sinclair ZX80 □ Sinclair ZX81 Telephone orders call
617-456-3661
23
FINALLY-A BATTERY BACKUP SUPPLY for
your Sinclair or MicroAce computer.
^1- ..»- -J^
/\ /\ /\ /v /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /\ /V /\ /V /V
''END LOST MEMORY DUE TO BLACKOUTS!'^
/V y'VfVrV'/VVfVoV /V /VVf Vf * /V*V<- •/'<•***
''Built-in NiCd rechargable battery
takes over should AC line go dead.
''Makes your ZX80/81 truly portable
-run for 2hrs . or more ANYWHERE!
* Vastly improves Glitch-rejection.
*8V pre- regulator lets your ZX run
cooler, with less chance of damage
*^1-. *-•- *-*-• *■*-- *-’•'* ■>•’-* *-*■*
/\ /\ /\ /\ /\ /\ /\ /\ /\ /V /\ /\ /\ /\ /\ /\ /\ /V /\ /\ /V /V /\ /V /V /V /\ /\ /V /V /\
Don't get annoyed by a sudden crash
before you order yours . Mail check
or MO for $84.50 ppd. , or send SASE
for specs and info. Cal. residents
add 67o sales tax. Model No. BBU-2
- SYNCWARE COMPANY -
4825 Elrovia Av. El Monte, Ca. 91732
*First 50 orders or inquiries get*
'■'FREE copy of our "Syncwars" pgm. 1*
16K from GREAT LAKES SOFTWARE I
All new software including games.
Business applications and muchmore.
Also, 16K RAM module now available
Write for FREE catalog to :
Great Lakes Software, 201 Burlington
Road, Valparaiso, IN 46383
''* Double your memory ** Run longer
Programs with easy to install kit,
complete &• instructions only $19.95
+1.95 - Rebates! Order today. Power
tronix 25 E.23 Bayonne, N.J. 07002
H\RV\RD
GRDU^
Bolton Road. Harvard, Mass. 01451
MORE GAMES FOR YOUR ZX81. . .
Five IK programs . $10.
Bandit, Chase, Life, Pong, Skeet.
Any two 16K programs
Bong
Checkbook
Solitaire
Biorhythm
Backgammon
Cat and Mouse
Guess the Animal
. $10.
Craps
Hangman
Checkers
Blackjack
Stock Market
Klingon Wars
3K TicTacToe
-- all programs on cassette tape --
Send check or money order to :
BIOCAL SOFTWARE
340 Cypress Drive
Fairfax, CA. 94930
ZX*ZX*ZX*ZX*ZX*ZX''ZX*ZX*ZX*ZX*ZX*ZX
''BANT A SOFTWARE NOW HAS PACK 'EM *
*IN MONZXER for $6.95 on tape. Gob-*
*ble up dots, avoid goblins; for 80s*
*or 81s . Football , Murder in the RAM*
*Casino, and Super Monzxer on tape*
*:$3.95 each. From our engineering*
*dpt:Beam Design & Pipe Flow$19.95*
*each. Coming soon: TANK SIGHT- BANTA*
''SOFTWARE, RD#7, Bethlehem, PA 18015 *
ZX*ZX*ZX*ZX*ZX*ZX*ZX*ZX*ZX*ZX*ZX*ZX
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Need freelance help to develope a
very low cost ZX printer. Todd
Miles, AArtic Mfg. , Inc 27 Canal
St., Millbury, Mass. 01527.
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First Class
U.S. Postage
PAID
Harvard, MA
Permit No. 8
■ 01451
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